Our research has led to the development of an improved caloric vestibular testing method whereby stimulus intensity can be conveniently controlled to preselected values while also reducing the time required to perform the test. The proposed research is intended to expand and verify this technique among patients and normal subjects. We plan to study variations in physical parameters among patients, as well as deliberate and inadvertent variations in the irrigation procedure, and to examine the effect of such variations upon computer-predicted response curves (expressed as nystagmus slow phase eye speed) as well as upon actual results of stimulation. Further modifications of the mathematical modeling of heat conduction in the labyrinth area will be explored. Normative performance will be studied when using air as well as water to perform the new caloric test procedure. A comparison of reliability between the irrigants air and water will be carried out. Optimum irrigation sequences and proper inter-test time intervals will be established. Alternative methods of detecting and scoring the responses to the new stimulus technique will be explored.